The statistics of primordial fluctuations imprinted in the Cosmic Microwave Background (CMB) and visible in the late-time clustering of galaxies is our most important window into the very early universe.
A measurement and characterization of the primordial fluctuations is necessary to improve our understanding of a putative period of inflation, shedding light on its microscopic origin. As future experiments achieve higher sensitivity and resolution, increasing the capacity to detect statistics beyond the two-point correlation function, i.e. non-Gaussianity [1]}, both CMB [2]}, [3]}, [4]}, [5]} and large scale structure (LSS) missions [6]}, [7]}, [8]}, [9]}, [10]}, [11]} will face challenges associated to removing foregrounds and taking into account non-primordial effects (see e.g. [12]}, [13]} and [14]}). Besides these systematic challenges, we run into limitations determined by the nature of the tracer field. For example, the CMB is fundamentally limited by two factors:
